LinuxLists.cc - [RFC][PATCH] Unify interface to persistent CMOS/RTC/whatever clock

2006-08-16 22:47:28

Subject: [RFC][PATCH] Unify interface to persistent CMOS/RTC/whatever clock

All,
Almost every arch has some form of persistent clock (CMOS, RTC, etc)
which is normally used at boot time to initialize xtime and
wall_to_monotonic. As part of the timekeeping consolidation, I propose
the following generic interface to the arch specific persistent clock:

unsigned long read_persistent_clock(void);

Which returns seconds since the epoch.

Having this interface allows for the xtime/wall_to_monotonic
initialization and management to be consolidated along with the rest of
the timekeeping core. Additionally it provides a common interface to a
low-res purely hardware driven clock, which is useful for watchdog
functionality as seen in the hangcheck-timer module.

My first pass at this can be found below. There are a few arches
(specifically: m32r, s390, sparc, sparc64) where I just didn't know what
to do, or where I suspect I didn't get it right, so I've CC'ed those
maintainers for suggestions.

I'll break this patch up before submitting it (using a generic weak
function we can go arch-by-arch), but I wanted to get it out there to
show I'm shooting for 100% coverage and see the initial reaction.

thanks
-john

arch/alpha/kernel/time.c | 77 +++++++++++++++++++++----------------------
arch/cris/kernel/crisksyms.c | 4 +-
arch/cris/kernel/time.c | 4 +-
arch/frv/kernel/time.c | 10 +++--
arch/h8300/kernel/time.c | 8 ++--
arch/i386/kernel/apm.c | 6 +--
arch/i386/kernel/time.c | 22 +++---------
arch/ia64/kernel/time.c | 14 +++----
arch/m32r/kernel/time.c | 6 +++
arch/m68k/kernel/time.c | 10 +++--
arch/m68knommu/kernel/time.c | 9 ++---
arch/mips/kernel/time.c | 11 ++----
arch/parisc/kernel/time.c | 19 +++-------
arch/powerpc/kernel/time.c | 4 +-
arch/ppc/kernel/time.c | 8 ++++
arch/s390/kernel/time.c | 6 +++
arch/sh/kernel/time.c | 20 +++++------
arch/sh64/kernel/time.c | 8 ++--
arch/sparc/kernel/time.c | 6 +++
arch/sparc64/kernel/time.c | 44 +++++++++++++-----------
arch/um/kernel/time.c | 9 ++---
arch/v850/kernel/time.c | 8 +++-
arch/x86_64/kernel/time.c | 12 +-----
arch/xtensa/kernel/time.c | 24 ++++++-------
kernel/timer.c | 8 +++-
25 files changed, 194 insertions(+), 163 deletions(-)

linux-2.6.18-rc4_timeofday-persistent-clock_C5.patch
============================================
diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c
index b191cc7..647f700 100644
--- a/arch/alpha/kernel/time.c
+++ b/arch/alpha/kernel/time.c
@@ -349,44 +349,6 @@ time_init(void)
bogomips yet, but this is close on a 500Mhz box. */
__delay(1000000);

- sec = CMOS_READ(RTC_SECONDS);
- min = CMOS_READ(RTC_MINUTES);
- hour = CMOS_READ(RTC_HOURS);
- day = CMOS_READ(RTC_DAY_OF_MONTH);
- mon = CMOS_READ(RTC_MONTH);
- year = CMOS_READ(RTC_YEAR);
-
- if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
- BCD_TO_BIN(sec);
- BCD_TO_BIN(min);
- BCD_TO_BIN(hour);
- BCD_TO_BIN(day);
- BCD_TO_BIN(mon);
- BCD_TO_BIN(year);
- }
-
- /* PC-like is standard; used for year >= 70 */
- epoch = 1900;
- if (year < 20)
- epoch = 2000;
- else if (year >= 20 && year < 48)
- /* NT epoch */
- epoch = 1980;
- else if (year >= 48 && year < 70)
- /* Digital UNIX epoch */
- epoch = 1952;
-
- printk(KERN_INFO "Using epoch = %d\n", epoch);
-
- if ((year += epoch) < 1970)
- year += 100;
-
- xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
- xtime.tv_nsec = 0;
-
- wall_to_monotonic.tv_sec -= xtime.tv_sec;
- wall_to_monotonic.tv_nsec = 0;
-
if (HZ > (1<<16)) {
extern void __you_loose (void);
__you_loose();
@@ -507,6 +469,45 @@ do_settimeofday(struct timespec *tv)

EXPORT_SYMBOL(do_settimeofday);

+/* Read the CMOS clock and convert it to epoch based seconds */
+unsigned long read_persistent_clock(void)
+{
+ unsigned int year, mon, day, hour, min, sec, epoch;
+
+ sec = CMOS_READ(RTC_SECONDS);
+ min = CMOS_READ(RTC_MINUTES);
+ hour = CMOS_READ(RTC_HOURS);
+ day = CMOS_READ(RTC_DAY_OF_MONTH);
+ mon = CMOS_READ(RTC_MONTH);
+ year = CMOS_READ(RTC_YEAR);
+
+ if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+ BCD_TO_BIN(sec);
+ BCD_TO_BIN(min);
+ BCD_TO_BIN(hour);
+ BCD_TO_BIN(day);
+ BCD_TO_BIN(mon);
+ BCD_TO_BIN(year);
+ }
+
+ /* PC-like is standard; used for year >= 70 */
+ epoch = 1900;
+ if (year < 20)
+ epoch = 2000;
+ else if (year >= 20 && year < 48)
+ /* NT epoch */
+ epoch = 1980;
+ else if (year >= 48 && year < 70)
+ /* Digital UNIX epoch */
+ epoch = 1952;
+
+ printk(KERN_INFO "Using epoch = %d\n", epoch);
+
+ if ((year += epoch) < 1970)
+ year += 100;
+
+ return = mktime(year, mon, day, hour, min, sec);
+}

/*
* In order to set the CMOS clock precisely, set_rtc_mmss has to be
diff --git a/arch/cris/kernel/crisksyms.c b/arch/cris/kernel/crisksyms.c
index 1f20c16..3d702c3 100644
--- a/arch/cris/kernel/crisksyms.c
+++ b/arch/cris/kernel/crisksyms.c
@@ -20,7 +20,7 @@
#include <asm/pgtable.h>
#include <asm/fasttimer.h>

-extern unsigned long get_cmos_time(void);
+extern unsigned long read_persistent_clock(void);
extern void __Udiv(void);
extern void __Umod(void);
extern void __Div(void);
@@ -32,7 +32,7 @@ extern void iounmap(volatile void * __io

/* Platform dependent support */
EXPORT_SYMBOL(kernel_thread);
-EXPORT_SYMBOL(get_cmos_time);
+EXPORT_SYMBOL(read_persistent_clock);
EXPORT_SYMBOL(loops_per_usec);

/* String functions */
diff --git a/arch/cris/kernel/time.c b/arch/cris/kernel/time.c
index 66ba889..329323c 100644
--- a/arch/cris/kernel/time.c
+++ b/arch/cris/kernel/time.c
@@ -168,7 +168,7 @@ int set_rtc_mmss(unsigned long nowtime)
/* grab the time from the RTC chip */

unsigned long
-get_cmos_time(void)
+read_persistent_clock(void)
{
unsigned int year, mon, day, hour, min, sec;

@@ -204,7 +204,7 @@ void
update_xtime_from_cmos(void)
{
if(have_rtc) {
- xtime.tv_sec = get_cmos_time();
+ xtime.tv_sec = read_persistent_clock();
xtime.tv_nsec = 0;
}
}
diff --git a/arch/frv/kernel/time.c b/arch/frv/kernel/time.c
index d5b64e1..c32659e 100644
--- a/arch/frv/kernel/time.c
+++ b/arch/frv/kernel/time.c
@@ -119,7 +119,8 @@ void time_divisor_init(void)
__set_TCSR_DATA(0, base >> 8);
}

-void time_init(void)
+
+unsigned long read_persistent_clock(void)
{
unsigned int year, mon, day, hour, min, sec;

@@ -135,9 +136,12 @@ void time_init(void)

if ((year += 1900) < 1970)
year += 100;
- xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
- xtime.tv_nsec = 0;
+ return mktime(year, mon, day, hour, min, sec);
+
+}

+void time_init(void)
+{
/* install scheduling interrupt handler */
setup_irq(IRQ_CPU_TIMER0, &timer_irq);

diff --git a/arch/h8300/kernel/time.c b/arch/h8300/kernel/time.c
index 688a510..18ea76c 100644
--- a/arch/h8300/kernel/time.c
+++ b/arch/h8300/kernel/time.c
@@ -48,7 +48,7 @@ static void timer_interrupt(int irq, voi
profile_tick(CPU_PROFILING, regs);
}

-void time_init(void)
+unsigned long read_persistent_clock(void)
{
unsigned int year, mon, day, hour, min, sec;

@@ -62,9 +62,11 @@ void time_init(void)

if ((year += 1900) < 1970)
year += 100;
- xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
- xtime.tv_nsec = 0;
+ return mktime(year, mon, day, hour, min, sec);
+}

+void time_init(void)
+{
platform_timer_setup(timer_interrupt);
}

diff --git a/arch/i386/kernel/apm.c b/arch/i386/kernel/apm.c
index 8591f2f..6d441ae 100644
--- a/arch/i386/kernel/apm.c
+++ b/arch/i386/kernel/apm.c
@@ -233,7 +233,7 @@

#include "io_ports.h"

-extern unsigned long get_cmos_time(void);
+extern unsigned long read_persistent_clock(void);
extern void machine_real_restart(unsigned char *, int);

#if defined(CONFIG_APM_DISPLAY_BLANK) && defined(CONFIG_VT)
@@ -1155,7 +1155,7 @@ out:
static void set_time(void)
{
if (got_clock_diff) { /* Must know time zone in order to set clock */
- xtime.tv_sec = get_cmos_time() + clock_cmos_diff;
+ xtime.tv_sec = read_persistent_clock() + clock_cmos_diff;
xtime.tv_nsec = 0;
}
}
@@ -1166,7 +1166,7 @@ static void get_time_diff(void)
/*
* Estimate time zone so that set_time can update the clock
*/
- clock_cmos_diff = -get_cmos_time();
+ clock_cmos_diff = -read_persistent_clock();
clock_cmos_diff += get_seconds();
got_clock_diff = 1;
#endif
diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
index edd00f6..571eb6c 100644
--- a/arch/i386/kernel/time.c
+++ b/arch/i386/kernel/time.c
@@ -203,7 +203,7 @@ irqreturn_t timer_interrupt(int irq, voi
}

/* not static: needed by APM */
-unsigned long get_cmos_time(void)
+unsigned long read_persistent_clock(void)
{
unsigned long retval;
unsigned long flags;
@@ -219,7 +219,7 @@ unsigned long get_cmos_time(void)

return retval;
}
-EXPORT_SYMBOL(get_cmos_time);
+EXPORT_SYMBOL(read_persistent_clock);

static void sync_cmos_clock(unsigned long dummy);

@@ -277,9 +277,9 @@ static int timer_suspend(struct sys_devi
/*
* Estimate time zone so that set_time can update the clock
*/
- clock_cmos_diff = -get_cmos_time();
+ clock_cmos_diff = -read_persistent_clock();
clock_cmos_diff += get_seconds();
- sleep_start = get_cmos_time();
+ sleep_start = read_persistent_clock();
return 0;
}

@@ -294,8 +294,8 @@ static int timer_resume(struct sys_devic
hpet_reenable();
#endif
setup_pit_timer();
- sec = get_cmos_time() + clock_cmos_diff;
- sleep_length = (get_cmos_time() - sleep_start) * HZ;
+ sec = read_persistent_clock() + clock_cmos_diff;
+ sleep_length = (read_persistent_clock() - sleep_start) * HZ;
write_seqlock_irqsave(&xtime_lock, flags);
xtime.tv_sec = sec;
xtime.tv_nsec = 0;
@@ -334,11 +334,6 @@ extern void (*late_time_init)(void);
/* Duplicate of time_init() below, with hpet_enable part added */
static void __init hpet_time_init(void)
{
- xtime.tv_sec = get_cmos_time();
- xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
-
if ((hpet_enable() >= 0) && hpet_use_timer) {
printk("Using HPET for base-timer\n");
}
@@ -359,10 +354,5 @@ void __init time_init(void)
return;
}
#endif
- xtime.tv_sec = get_cmos_time();
- xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
-
time_init_hook();
}
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 6928ef0..57f119d 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -240,18 +240,18 @@ void __devinit ia64_disable_timer(void)
ia64_set_itv(1 << 16);
}

+unsigned long read_persistent_clock(void)
+{
+ struct timespec ts;
+ efi_gettimeofday(&ts);
+ return ts.tv_sec;
+}
+
void __init
time_init (void)
{
register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
- efi_gettimeofday(&xtime);
ia64_init_itm();
-
- /*
- * Initialize wall_to_monotonic such that adding it to xtime will yield zero, the
- * tv_nsec field must be normalized (i.e., 0 <= nsec < NSEC_PER_SEC).
- */
- set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
}

/*
diff --git a/arch/m32r/kernel/time.c b/arch/m32r/kernel/time.c
index ded0be0..eebf379 100644
--- a/arch/m32r/kernel/time.c
+++ b/arch/m32r/kernel/time.c
@@ -240,6 +240,12 @@ irqreturn_t timer_interrupt(int irq, voi
struct irqaction irq0 = { timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE,
"MFT2", NULL, NULL };

+/* XXX - Need some help here! */
+unsigned long read_persistent_clock(void)
+{
+ return 0;
+}
+
void __init time_init(void)
{
unsigned int epoch, year, mon, day, hour, min, sec;
diff --git a/arch/m68k/kernel/time.c b/arch/m68k/kernel/time.c
index 98e4b1a..56b51e2 100644
--- a/arch/m68k/kernel/time.c
+++ b/arch/m68k/kernel/time.c
@@ -72,7 +72,7 @@ static irqreturn_t timer_interrupt(int i
return IRQ_HANDLED;
}

-void time_init(void)
+static unsigned long read_persistent_clock(void)
{
struct rtc_time time;

@@ -81,12 +81,14 @@ void time_init(void)

if ((time.tm_year += 1900) < 1970)
time.tm_year += 100;
- xtime.tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday,
+ return mktime(time.tm_year, time.tm_mon, time.tm_mday,
time.tm_hour, time.tm_min, time.tm_sec);
- xtime.tv_nsec = 0;
}
- wall_to_monotonic.tv_sec = -xtime.tv_sec;
+ return 0;
+}

+void time_init(void)
+{
mach_sched_init(timer_interrupt);
}

diff --git a/arch/m68knommu/kernel/time.c b/arch/m68knommu/kernel/time.c
index 1db9872..2db1557 100644
--- a/arch/m68knommu/kernel/time.c
+++ b/arch/m68knommu/kernel/time.c
@@ -100,7 +100,7 @@ static irqreturn_t timer_interrupt(int i
return(IRQ_HANDLED);
}

-void time_init(void)
+static unsigned long read_persistent_clock(void)
{
unsigned int year, mon, day, hour, min, sec;

@@ -111,10 +111,11 @@ void time_init(void)

if ((year += 1900) < 1970)
year += 100;
- xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
- xtime.tv_nsec = 0;
- wall_to_monotonic.tv_sec = -xtime.tv_sec;
+ return mktime(year, mon, day, hour, min, sec);
+}

+void time_init(void)
+{
mach_sched_init(timer_interrupt);
}

diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c
index 170cb67..abac10c 100644
--- a/arch/mips/kernel/time.c
+++ b/arch/mips/kernel/time.c
@@ -625,6 +625,11 @@ static unsigned int __init calibrate_hpt
return frequency >> log_2_loops;
}

+unsigned long read_persistent_clock(void)
+{
+ return rtc_mips_get_time();
+}
+
void __init time_init(void)
{
if (board_time_init)
@@ -633,12 +638,6 @@ void __init time_init(void)
if (!rtc_mips_set_mmss)
rtc_mips_set_mmss = rtc_mips_set_time;

- xtime.tv_sec = rtc_mips_get_time();
- xtime.tv_nsec = 0;
-
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
-
/* Choose appropriate high precision timer routines. */
if (!cpu_has_counter && !mips_hpt_read) {
/* No high precision timer -- sorry. */
diff --git a/arch/parisc/kernel/time.c b/arch/parisc/kernel/time.c
index 5facc9b..c837d29 100644
--- a/arch/parisc/kernel/time.c
+++ b/arch/parisc/kernel/time.c
@@ -225,6 +225,13 @@ unsigned long long sched_clock(void)
return (unsigned long long)jiffies * (1000000000 / HZ);
}

+unsigned long read_persistent_clock(void)
+{
+ struct tod_data;
+ if(pdc_tod_read(&tod_data))
+ return 0;
+ return tod.tod_sec;
+}

void __init time_init(void)
{
@@ -243,17 +250,5 @@ void __init time_init(void)
/* kick off Itimer (CR16) */
mtctl(next_tick, 16);

- if(pdc_tod_read(&tod_data) == 0) {
- write_seqlock_irq(&xtime_lock);
- xtime.tv_sec = tod_data.tod_sec;
- xtime.tv_nsec = tod_data.tod_usec * 1000;
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
- write_sequnlock_irq(&xtime_lock);
- } else {
- printk(KERN_ERR "Error reading tod clock\n");
- xtime.tv_sec = 0;
- xtime.tv_nsec = 0;
- }
}

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 774c0a3..c5e87eb 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -913,7 +913,7 @@ void __init generic_calibrate_decr(void)
#endif
}

-unsigned long get_boot_time(void)
+unsigned long read_persistent_clock(void)
{
struct rtc_time tm;

@@ -1011,7 +1011,7 @@ void __init time_init(void)
tb_to_ns_scale = scale;
tb_to_ns_shift = shift;

- tm = get_boot_time();
+ tm = read_persistent_clock();

write_seqlock_irqsave(&xtime_lock, flags);

diff --git a/arch/ppc/kernel/time.c b/arch/ppc/kernel/time.c
index 6ab8cc7..59b58e9 100644
--- a/arch/ppc/kernel/time.c
+++ b/arch/ppc/kernel/time.c
@@ -281,6 +281,14 @@ int do_settimeofday(struct timespec *tv)

EXPORT_SYMBOL(do_settimeofday);

+unsigned long read_persistent_clock(void)
+{
+ int sec = 0;
+ if (ppc_md.get_rtc_time)
+ sec = ppc_md.get_rtc_time();
+ return sec;
+}
+
/* This function is only called on the boot processor */
void __init time_init(void)
{
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 74e6178..b1e62b4 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -341,6 +341,12 @@ void init_cpu_timer(void)

extern void vtime_init(void);

+unsigned long read_persistent_clock(void)
+{
+ /* XXX I have no clue here. s390 folks, help! */
+ return 0;
+}
+
/*
* Initialize the TOD clock and the CPU timer of
* the boot cpu.
diff --git a/arch/sh/kernel/time.c b/arch/sh/kernel/time.c
index a1589f8..cf5c5ec 100644
--- a/arch/sh/kernel/time.c
+++ b/arch/sh/kernel/time.c
@@ -161,6 +161,16 @@ device_initcall(timer_init_sysfs);

void (*board_time_init)(void);

+unsigned long read_persistent_clock(void)
+{
+ struct timespec ts;
+ if (rtc_get_time) {
+ rtc_get_time(&ts);
+ return ts.tv_sec;
+ }
+ return 0;
+}
+
void __init time_init(void)
{
if (board_time_init)
@@ -168,16 +178,6 @@ void __init time_init(void)

clk_init();

- if (rtc_get_time) {
- rtc_get_time(&xtime);
- } else {
- xtime.tv_sec = mktime(2000, 1, 1, 0, 0, 0);
- xtime.tv_nsec = 0;
- }
-
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
-
/*
* Find the timer to use as the system timer, it will be
* initialized for us.
diff --git a/arch/sh64/kernel/time.c b/arch/sh64/kernel/time.c
index b8162e5..d6feac5 100644
--- a/arch/sh64/kernel/time.c
+++ b/arch/sh64/kernel/time.c
@@ -487,6 +487,11 @@ static irqreturn_t sh64_rtc_interrupt(in
static struct irqaction irq0 = { timer_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "timer", NULL, NULL};
static struct irqaction irq1 = { sh64_rtc_interrupt, IRQF_DISABLED, CPU_MASK_NONE, "rtc", NULL, NULL};

+unsigned long read_persistent_clock(void)
+{
+ return get_rtc_time();
+}
+
void __init time_init(void)
{
unsigned int cpu_clock, master_clock, bus_clock, module_clock;
@@ -511,9 +516,6 @@ void __init time_init(void)
panic("Unable to remap CPRC\n");
}

- xtime.tv_sec = get_rtc_time();
- xtime.tv_nsec = 0;
-
setup_irq(TIMER_IRQ, &irq0);
setup_irq(RTC_IRQ, &irq1);

diff --git a/arch/sparc/kernel/time.c b/arch/sparc/kernel/time.c
index 845081b..21c25ea 100644
--- a/arch/sparc/kernel/time.c
+++ b/arch/sparc/kernel/time.c
@@ -366,6 +366,12 @@ static int __init clock_init(void)
fs_initcall(clock_init);
#endif /* !CONFIG_SUN4 */

+unsigned long read_persistent_clock(void)
+{
+ /* XXX - help! not quite sure what to do here. */
+ return 0;
+}
+
void __init sbus_time_init(void)
{

diff --git a/arch/sparc64/kernel/time.c b/arch/sparc64/kernel/time.c
index 094d3e3..df48592 100644
--- a/arch/sparc64/kernel/time.c
+++ b/arch/sparc64/kernel/time.c
@@ -606,23 +606,9 @@ static int __init has_low_battery(void)
return (data1 == data2); /* Was the write blocked? */
}

-/* Probe for the real time clock chip. */
-static void __init set_system_time(void)
+unsigned long read_persistent_clock(void)
{
- unsigned int year, mon, day, hour, min, sec;
void __iomem *mregs = mstk48t02_regs;
-#ifdef CONFIG_PCI
- unsigned long dregs = ds1287_regs;
-#else
- unsigned long dregs = 0UL;
-#endif
- u8 tmp;
-
- if (!mregs && !dregs) {
- prom_printf("Something wrong, clock regs not mapped yet.\n");
- prom_halt();
- }
-
if (mregs) {
spin_lock_irq(&mostek_lock);

@@ -637,6 +623,7 @@ static void __init set_system_time(void)
day = MSTK_REG_DOM(mregs);
mon = MSTK_REG_MONTH(mregs);
year = MSTK_CVT_YEAR( MSTK_REG_YEAR(mregs) );
+ spin_unlock_irq(&mostek_lock);
} else {
/* Dallas 12887 RTC chip. */

@@ -649,7 +636,8 @@ static void __init set_system_time(void)
year = CMOS_READ(RTC_YEAR);
} while (sec != CMOS_READ(RTC_SECONDS));

- if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+ if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
+ || RTC_ALWAYS_BCD) {
BCD_TO_BIN(sec);
BCD_TO_BIN(min);
BCD_TO_BIN(hour);
@@ -660,13 +648,29 @@ static void __init set_system_time(void)
if ((year += 1900) < 1970)
year += 100;
}
+ return mktime(year, mon, day, hour, min, sec);
+}

- xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
- xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
+/* Probe for the real time clock chip. */
+static void __init set_system_time(void)
+{
+ unsigned int year, mon, day, hour, min, sec;
+ void __iomem *mregs = mstk48t02_regs;
+#ifdef CONFIG_PCI
+ unsigned long dregs = ds1287_regs;
+#else
+ unsigned long dregs = 0UL;
+#endif
+ u8 tmp;
+
+ if (!mregs && !dregs) {
+ prom_printf("Something wrong, clock regs not mapped yet.\n");
+ prom_halt();
+ }

+ /* XXX - I probably messed this bit up. HELP! */
if (mregs) {
+ spin_lock_irq(&mostek_lock);
tmp = mostek_read(mregs + MOSTEK_CREG);
tmp &= ~MSTK_CREG_READ;
mostek_write(mregs + MOSTEK_CREG, tmp);
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index 552ca1c..85c56ae 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -123,13 +123,14 @@ static void register_timer(void)

extern void (*late_time_init)(void);

+unsigned long read_persistent_clock(void)
+{
+ return (long)os_nsecs()/BILLION;
+}
+
void time_init(void)
{
long long nsecs;
-
- nsecs = os_nsecs();
- set_normalized_timespec(&wall_to_monotonic, -nsecs / BILLION,
- -nsecs % BILLION);
late_time_init = register_timer;
}

diff --git a/arch/v850/kernel/time.c b/arch/v850/kernel/time.c
index a0b4669..dea2753 100644
--- a/arch/v850/kernel/time.c
+++ b/arch/v850/kernel/time.c
@@ -184,8 +184,14 @@ static struct irqaction timer_irqaction
NULL
};

+unsigned long read_persistent_clock(void)
+{
+ struct timespec ts;
+ mach_gettimeofday(&ts);
+ return ts.tv_sec;
+}
+
void time_init (void)
{
- mach_gettimeofday (&xtime);
mach_sched_init (&timer_irqaction);
}
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 7a9b182..343461b 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -511,7 +511,7 @@ unsigned long long sched_clock(void)
return cycles_2_ns(a);
}

-static unsigned long get_cmos_time(void)
+static unsigned long read_persistent_clock(void)
{
unsigned int year, mon, day, hour, min, sec;
unsigned long flags;
@@ -901,12 +901,6 @@ void __init time_init(void)
if (nohpet)
vxtime.hpet_address = 0;

- xtime.tv_sec = get_cmos_time();
- xtime.tv_nsec = 0;
-
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
-
if (!hpet_init())
vxtime_hz = (FSEC_PER_SEC + hpet_period / 2) / hpet_period;
else
@@ -1018,7 +1012,7 @@ static int timer_suspend(struct sys_devi
/*
* Estimate time zone so that set_time can update the clock
*/
- long cmos_time = get_cmos_time();
+ long cmos_time = read_persistent_clock();

clock_cmos_diff = -cmos_time;
clock_cmos_diff += get_seconds();
@@ -1030,7 +1024,7 @@ static int timer_resume(struct sys_devic
{
unsigned long flags;
unsigned long sec;
- unsigned long ctime = get_cmos_time();
+ unsigned long ctime = read_persistent_clock();
unsigned long sleep_length = (ctime - sleep_start) * HZ;

if (vxtime.hpet_address)
diff --git a/arch/xtensa/kernel/time.c b/arch/xtensa/kernel/time.c
index 412ab32..3588484 100644
--- a/arch/xtensa/kernel/time.c
+++ b/arch/xtensa/kernel/time.c
@@ -56,10 +56,19 @@ static struct irqaction timer_irqaction
.name = "timer",
};

-void __init time_init(void)
+
+unsigned long read_persistent_clock(void)
{
time_t sec_o, sec_n = 0;
+ if (platform_get_rtc_time(&sec_o) == 0)
+ while (platform_get_rtc_time(&sec_n))
+ if (sec_o != sec_n)
+ break;
+ return sec_n;
+}

+void __init time_init(void)
+{
/* The platform must provide a function to calibrate the processor
* speed for the CALIBRATE.
*/
@@ -71,20 +80,9 @@ void __init time_init(void)
(int)(ccount_per_jiffy/(10000/HZ))%100);
#endif

- /* Set time from RTC (if provided) */
-
- if (platform_get_rtc_time(&sec_o) == 0)
- while (platform_get_rtc_time(&sec_n))
- if (sec_o != sec_n)
- break;
-
- xtime.tv_nsec = 0;
- last_rtc_update = xtime.tv_sec = sec_n;
+ last_rtc_update = xtime.tv_sec;
last_ccount_stamp = get_ccount();

- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
-
/* Initialize the linux timer interrupt. */

setup_irq(LINUX_TIMER_INT, &timer_irqaction);
diff --git a/kernel/timer.c b/kernel/timer.c
index b650f04..6ce2fd9 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -961,10 +961,16 @@ void __init timekeeping_init(void)
unsigned long flags;

write_seqlock_irqsave(&xtime_lock, flags);
+ ntp_clear();
+
clock = clocksource_get_next();
clocksource_calculate_interval(clock, tick_nsec);
clock->cycle_last = clocksource_read(clock);
- ntp_clear();
+
+ xtime.tv_sec = read_persistent_clock();
+ xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
+ set_normalized_timespec(&wall_to_monotonic,
+ -xtime.tv_sec, -xtime.tv_nsec);
write_sequnlock_irqrestore(&xtime_lock, flags);
}

2006-08-17 01:50:32

by john stultz

[permalink] [raw]

On Saturday 19 August 2006 9:39 am, David Brownell wrote:
> > So if we go w/ the "it may not be available, so always assume it isn't"
> > way of thinking, it forces us to rely upon the RTC driver(s) to resume
> > time (which means every RTC, no matter how simple has to have
> > suspend/resume hooks and call settimeofday at least).
>
> No, that was the point of my comment about using the new class level
> suspend/resume calls. The RTC drivers wouldn't be responsible for
> that; the RTC framework would be. RTC drivers may still want the
> suspend/resume hooks to make sure they issue system wakeup events,
> and so on, but no longer for maintaining the wall clock. I'll send
> a patch (of the "it compiles" type) later.

Welcome to "later"!

------------------------

Preliminary RTC class suspend/resume support:

- Inlining the same code used by ARM, save and restore the delta between
a selected RTC and the current system time.

- Removes calls to that ARM code from the AT91 and S3C RTCs; the AT91
calls are left as stubs, because a pending patch still needs those
(currently empty) routines to properly issue system wakeup events.

- Selects rtc0 by default, else CONFIG_RTC_HCTOSYS_DEVICE. We expect all RTCs
to be powered during "real" sleep states, but swsusp/hibernation requires
something that's also battery-backed.

Depends on new class suspend/resume methods, added by a patch in the MM tree.

(Preliminary because untested, and because of a FIXME ... nothing recovers
from unregistering the selected RTC; that could happen only with badly written
RTC drivers though.)

Index: g26/drivers/rtc/class.c
===================================================================
--- g26.orig/drivers/rtc/class.c 2006-08-19 09:20:36.000000000 -0700
+++ g26/drivers/rtc/class.c 2006-08-19 09:20:37.000000000 -0700
@@ -29,6 +29,86 @@ static void rtc_device_release(struct cl
kfree(rtc);
}

+#ifdef CONFIG_PM
+
+/*
+ * Re-initialize wall clock on resume, to match the delta (calculated
+ * during suspend) between that and an appropriate RTC.
+ *
+ * We assume any RTC is good enough, meaning it stays running during
+ * system sleep states; but prefer the CONFIG_RTC_HCTOSYS_DEVICE on
+ * the grounds that it's expected to be battery-backed and thus will
+ * stay running even during the "off" states used by swsusp.
+ *
+ * REVISIT ... we should probably have a way to tell if a given RTC
+ * will stay powered during the target system state, rather than just
+ * assume a "valid" configuration (where no RTC that powers off will
+ * be selected, and no selected RTC will be removed). That could let
+ * us get rid of the need for CONFIG_RTC_HCTOSYS_DEVICE too...
+ */
+
+static struct class_device *sleep_rtc;
+static struct timespec delta;
+
+static int rtc_suspend(struct device *dev, pm_message_t mesg)
+{
+ struct rtc_time tm;
+ struct timespec time;
+
+ if (!sleep_rtc || dev != sleep_rtc->dev)
+ return 0;
+
+ time.tv_nsec = 0;
+
+ rtc_read_time(sleep_rtc, &tm);
+ rtc_tm_to_time(&tm, &time.tv_sec);
+
+ set_normalized_timespec(&delta,
+ xtime.tv_sec - time.tv_sec,
+ xtime.tv_nsec - time.tv_nsec);
+
+ pr_debug("%s: %s %4d-%02d-%02d %02d:%02d:%02d\n",
+ sleep_rtc->class_id, "suspend",
+ 1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,
+ tm.tm_hour, tm.tm_min, tm.tm_sec);
+
+ return 0;
+}
+
+static int rtc_resume(struct device *dev)
+{
+ struct rtc_time tm;
+ struct timespec time;
+
+ /* REVISIT some swsusp configurations may feed us an RTC that
+ * lost power ... we should probably try detecting that, and
+ * refuse to update the time using a bogus clock.
+ */
+
+ if (!sleep_rtc || dev != sleep_rtc->dev)
+ return 0;
+
+ time.tv_nsec = 0;
+
+ rtc_read_time(sleep_rtc, &tm);
+ rtc_tm_to_time(&tm, &time.tv_sec);
+
+ set_normalized_timespec(&time,
+ xtime.tv_sec - time.tv_sec,
+ xtime.tv_nsec - time.tv_nsec);
+ do_settimeofday(&time);
+
+ pr_debug("%s: %s %4d-%02d-%02d %02d:%02d:%02d\n",
+ sleep_rtc->class_id, "resume",
+ 1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,
+ tm.tm_hour, tm.tm_min, tm.tm_sec);
+
+ return 0;
+}
+
+#endif
+
+
/**
* rtc_device_register - register w/ RTC class
* @dev: the device to register
@@ -85,6 +165,21 @@ struct rtc_device *rtc_device_register(c
if (err)
goto exit_kfree;

+#ifdef CONFIG_PM
+ mutex_lock(&idr_lock);
+#ifdef CONFIG_RTC_HCTOSYS_DEVICE
+ if (sleep_rtc && strncmp(rtc->class_dev.class_id,
+ CONFIG_RTC_HCTOSYS_DEVICE,
+ BUS_ID_SIZE) == 0) {
+ rtc_class_close(sleep_rtc);
+ sleep_rtc = NULL;
+ }
+#endif
+ if (!sleep_rtc)
+ sleep_rtc = rtc_class_open(rtc->class_dev.class_id);
+ mutex_unlock(&idr_lock);
+#endif
+
dev_info(dev, "rtc core: registered %s as %s\n",
rtc->name, rtc->class_dev.class_id);

@@ -113,6 +208,17 @@ EXPORT_SYMBOL_GPL(rtc_device_register);
*/
void rtc_device_unregister(struct rtc_device *rtc)
{
+#ifdef CONFIG_PM
+ mutex_lock(&idr_lock);
+ if (&rtc->class_dev == sleep_rtc) {
+ rtc_class_close(sleep_rtc);
+ sleep_rtc = NULL;
+ /* FIXME */
+ printk(KERN_WARNING "rtc: now what to use during sleep??\n");
+ }
+ mutex_unlock(&idr_lock);
+#endif
+
mutex_lock(&rtc->ops_lock);
rtc->ops = NULL;
mutex_unlock(&rtc->ops_lock);
@@ -134,6 +240,10 @@ static int __init rtc_init(void)
printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
return PTR_ERR(rtc_class);
}
+#ifdef CONFIG_PM
+ rtc_class->suspend = rtc_suspend;
+ rtc_class->resume = rtc_resume;
+#endif
return 0;
}

Index: g26/drivers/rtc/rtc-at91.c
===================================================================
--- g26.orig/drivers/rtc/rtc-at91.c 2006-08-19 09:20:36.000000000 -0700
+++ g26/drivers/rtc/rtc-at91.c 2006-08-19 09:20:37.000000000 -0700
@@ -339,38 +339,13 @@ static struct timespec at91_rtc_delta;

static int at91_rtc_suspend(struct platform_device *pdev, pm_message_t state)
{
- struct rtc_time tm;
- struct timespec time;
-
- time.tv_nsec = 0;
-
- /* calculate time delta for suspend */
- at91_rtc_readtime(&pdev->dev, &tm);
- rtc_tm_to_time(&tm, &time.tv_sec);
- save_time_delta(&at91_rtc_delta, &time);
-
- pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
- 1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,
- tm.tm_hour, tm.tm_min, tm.tm_sec);
-
+ /* STUB, pending merge of rtc wakeup patch */
return 0;
}

static int at91_rtc_resume(struct platform_device *pdev)
{
- struct rtc_time tm;
- struct timespec time;
-
- time.tv_nsec = 0;
-
- at91_rtc_readtime(&pdev->dev, &tm);
- rtc_tm_to_time(&tm, &time.tv_sec);
- restore_time_delta(&at91_rtc_delta, &time);
-
- pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
- 1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,
- tm.tm_hour, tm.tm_min, tm.tm_sec);
-
+ /* STUB, pending merge of rtc wakeup patch */
return 0;
}
#else
Index: g26/drivers/rtc/rtc-s3c.c
===================================================================
--- g26.orig/drivers/rtc/rtc-s3c.c 2006-08-19 09:20:36.000000000 -0700
+++ g26/drivers/rtc/rtc-s3c.c 2006-08-19 09:20:37.000000000 -0700
@@ -536,37 +536,15 @@ static int ticnt_save;

static int s3c_rtc_suspend(struct platform_device *pdev, pm_message_t state)
{
- struct rtc_time tm;
- struct timespec time;
-
- time.tv_nsec = 0;
-
/* save TICNT for anyone using periodic interrupts */
-
ticnt_save = readb(S3C2410_TICNT);
-
- /* calculate time delta for suspend */
-
- s3c_rtc_gettime(&pdev->dev, &tm);
- rtc_tm_to_time(&tm, &time.tv_sec);
- save_time_delta(&s3c_rtc_delta, &time);
s3c_rtc_enable(pdev, 0);
-
return 0;
}

static int s3c_rtc_resume(struct platform_device *pdev)
{
- struct rtc_time tm;
- struct timespec time;
-
- time.tv_nsec = 0;
-
s3c_rtc_enable(pdev, 1);
- s3c_rtc_gettime(&pdev->dev, &tm);
- rtc_tm_to_time(&tm, &time.tv_sec);
- restore_time_delta(&s3c_rtc_delta, &time);
-
writeb(ticnt_save, S3C2410_TICNT);
return 0;
}